Target display system



March 22, 1960 H. M. Asul'rl-l 2,930,036

TARGET DISPLAY SYSTEM Filed March 3, 1954 3 Sheets-Sheet 1 March 22,1960 H. M. AsQUlTH 2,930,036

TARGET DISPLAY SYSTEM Filed March 3, 1954 l 3 Sheets-Sheet 2 TARGET upAND TARGET DawN AND To THE RIGHT y m mE RIGHT 30 I FIG. 2 c FVG. 2a\

TARGET DowN AND TARGET -ro TO THE LEFT' THE RIGHT F'lG. 2 e

TARGET up AND "ON TARGET" T0 THE LEFT AT FIRING @NGE ATTDRNEY March 22,1960 H. M. AsQul'rH TARGET DISPLAY SYSTEM Filed March 3, 1954 3Sheets-SheerI 3 R, www m ,V W 4 h V Mw 3^ 9 f 5 f Vf M w je b c 3 r. D,

i .being followed by, the sighted target.

Unidnsats {Plafef 2,930,036 "maaar DISPLAY svsrnM.

Harold M. Asquith, Hyde Park, Mass., assigner to Raytheon Company, a.corporation of Delaware.

Appaction M 'rch 3,.1054","Sen1 No. 413,313 5 l claims. (cl. 343-17)broad concepts of the-,invention are also applicable in othersettingsand to other equipment, and forpurposes other than military, as will beapparent as the description proceeds.

Most radar equipmentis based upon the transmission and reception ofpulses ofl electromagnetic energy `of very short duration. Thepulse-echo processis repeated periodically at a rate so rapid that thedetection of a target causes asteadypimage to be obtained in va cathoderay tube. This image appears as a tiny spot of. illumina? tion'ontheface of the otherwise unilluminated screen, or window,` constituting thevisual indicator, or scope Being such a tiny spot, and of variableclarity, this indication leaves much to be desired from anintelligencecommunicating standpoint. Moreover, since the spot is staticlandA ofgno distinctive contour, it. lconveys no informationper se, as,to the specific attitude of, or course For the same reasonsit fails tonotify the interceptor pilot of the exact maneuver heshould adopt tobring his craft onto the collisionrcourse, that is, a course calculatedtoreduce as quickly as possible the spatial ydistance between thesighted :craft and his own.

The .present invention provides a method andrmeans whereby there will bepresented to the eye of the interceptor pilot an illuminatedimage ofvsignificant contour, significant attitude and significant positioning;the

`contour being such asto ,indicate the distance to be .traversed toreach the detected target, the attitude being such' as to indicate theapproximate .attitude into which the-pilot should maneuver his own craftt'o achieve the optimum attaching lcourse, and the ypositioningv beingsuch as to indicate vthe angle of deviation of the target from his ownline of flight. Y

In the illustrated embodiment, the' illuminated image has an appearanceclosely resembling that of ya common type of interceptor aircraft; theresemblance being-so close that the attitude assumed by the imagewill.con vey instantly to the pilot the desired'information concerningthe attitude into which his own plane should bel maneuvered. Moreover,since a Vpilots reexes are conditioned, by habit, to execute aparticular muscular action upon presentation to his optical senses ofthe particular image to which `such muscular action is causativelyrelated, the correctmanipulation of Athe pilots control levers(fjoysticlC etc.) will occur instinctively, as it were, as an immediateresponse toabsorptions ofthe `image Ainto the opticrsenses, and withoutthe time lag, or possibility of error, which deliberate mentalVprocesses would entail.

These and other characteristics of the invention will bebetterunderstood upon reference lto, the following description/of theembodiment of the invention illustrated in the accompanying drawingswherein: jFig. 1 is a schematic representation of apparatus suitable`for producing upon a cathode ray screen an image of contour, attitudeand position indicative of the maneuver for execution by thejpilot vforthe purpose of establishing closer approach to interception of a target.sighted by Vthe antennaY assembly of Fig. 1; Figs. 2a to. 2f,inclusive, show examples of images appearing under the indicatedconditions; Figs. 3a to 3d, inclusive, show the pulse transformationcycle; and Figs. 4, 5 and show representative pulse patterns.

Referring to Fig. 1, reference numeral designates an antenna reflectorbowl mounted on a gimbal frame 11 in conventional fashion forfrotationin azimuth and elevation vin relation to said frame; the gimbal frame 11being rigid with the body of the aircraft upon which it is mounted. Thecraft is equipped with radar transmitting apparatus including a T.R.waveguide assembly 12 terminating in antenna 13 which coacts withantenna reflector 10 in sending out radiant energy for intercep tion bya sought object which may be an airfield beacon or other fixed object,but is herein assumed to be an enemy aircraft upon which it is desiredto train the guns or other missiles carried by the interceptor craftupon which the apparatus of Fig. 1 is mounted.

The.v radiant energy reflected back to antenna 13 by the said enemycraft passes back through T.R. waveguide assembly 12 to conventionalreceiver circuitry 14 including frequency modulating and detection meansfor obtaining a D.C. voltage output having horizontal and Verticalcomponents whose respective magnitudes reect the respective azimuthand'elevation directional components of the angleof deviation of thesighted enemy craft with respect to the line of ight of the interceptorcraft. These horizontal and vertical voltage components, as derived inunits 16 and 17, are supplied to control valves 18 and 19 of thetrackingmechanism and thusV produce actuation of the antenna positioninghydraulic servo-motors 21 and 22, respectively, to maintain the antennain tracking relationship to the detected enemy craft;the servo 21'operating to vary the angle of elevation of the antenna assembly and theservo 22 to vary the azimuth angle of the antenna assembly.

VIn the present invention, instead of supplying the positional voltagecomponents directly to the horizontal and vertical deflection plates 31and 32 of the cathode ray tube 30 as in conventional practice, Vthe saiddirect connection procedure of the prior art is superseded by a methodinvolving the following steps: first, the reproduction of the twoorthogonal motion components of Vthe antenna assembly in two remotelydisposed synchro resolvers (indicated at 35 and 37 in Fig. 1); second,the generation of oscillations of relatively low frequency and theshaping of said oscillating energy to square pulse form; third, thedifferentiating and time-modulating of said pulses to cause theirsuperpositioning in a manner that will produce two parallel lightstreaks of unequal length but symmetrical design, simulating the wingsand tail of an aircraft, whenY displayed on the uorescent screen ofcathode ray tube 30; fourth, the feeding of said pulses to the azimuthsynchro resolver 36, where they are divided vectorially to correspond tothe angle through' which the resolver has been rotated in reproducingthe degree of departure of the antenna assembly, in azimuth, from thelongitudinal axis of the craft; fth, the feeding into the elevationsynchro resolver of Qthe generated oscillations in the form of a sinewave whose amplitude is` adjusted to correspond to the degree .ofrotation of the elevation synchro resolver from the horizontal referenceplane; sixth, the amplification and range-v voltage controlledattenuation of the vectorially divided and amplitude-corrected pulsesresulting from steps 2, 3, and 4; seventh, the application of D.C.voltages to the output resulting from step No. 5; and eighth, thedelivery of the combined product of steps 2, 3, 4'and v5 to therespective horizontal and vertical deection plates-of tube 30, toproduce on the tube screen an illuminated image of an aircraft, theimage including two parallel streaks and a connecting verticallydisposed streak, with the size of the image components beingproportional tothe de gree of range-voltage controlled attenuationproduced in step No. 5, with the angle of inclination corresponding tothe vectorial division producedin step/No. 3, and with the length of theconnecting vertical streak being proportional to the sine waveamplitudeas adjusted in step No. 4.

A pictorial representation of vvthe aircraftjlifelike in appearanceisthuspresented on the radarscope 30. L'Ihe positioning of the wings inrelationto the tail A(above as in Fig. 4 or below as yinl-"ig 5)simulates -the appearance of a craft climbing or diving, andindicatestotle pilot of the interceptor craft that he is to climb ordive to boresight his guns on the target. The parallel linesrepresenting the wings and tail bank to the right or left, representingto the pilot that he is to bank his plane to the right or left to alignhis guns with the target. Simultaneously, with the change of attitude ofthe simulated target, the position on the scope changes, vthat is, ifthe target is to the right on the scope, the wings and tail bank right.When the target is above the center of the scope, the target appears tobe climbing as the wings are above the tail. An interception course isthen attained by maneuvering to place the target in the center of thescope and in an attitude such that the wings and tail are lined up inelevation and are not banked, similar to the appearance of a plane deadahead.

Returning to the Fig. l diagram, the components involved in reproducingthe horizontal and vertical vectorial components of the antenna bowlsrotation are the electric servo motors 48 and 49 energized fromamplifying sources 46 and 47, respectively, with the respective degreesof energization being controlled by lthe variation of resistanceincluded in the excitation circuits 43 and 44 as the resistanceadjusting arms 41 and 42 follow the respective motions of the antennapositioning hydraulic servos 22 and 21 heretofore referred to.

Rotation of electric servos 48 and 49 is communicated to the synchroresolvers 36 and 37, respectively, by way of the interposed speedreducing gear trains 51 and 52, to which lare connected synchronouslyshiftable potentiometers 53 and 54, respectively, to feed back into theservo-amplifiers 46 and 47 the proportionate follow-up voltagerestoration values for restoring equilibrium.

The degree of rotation thus imparted -to azimuth synchro resolver 36constitutes the measurement for establishing the relative magnitudes ofthe horizontal and vertical vectors into which the resolver 36 dividesthe pulses successively received from the square wave pulse forming andcombining units 61, 62, and 63; the said horizontal and vertical vectorsbeing the orthogonal components of the angle through which the resolver36 has rotated with respect .to its zero (longitudinal axis) position.

The square wave pulse forming and combining units include a ninety-cycleoscillator 61 to generate the basic it wave, and a pulse former 62 tosquarethe Wave and effect a first differentiation thereof, therebyproducing a pulse fragment suggestive of one side of the wing of anaircraft, together with the opposite side of the same crafts tail; thebasic sine wave being indicated in Fig. 3a, the square wave resultant inFig. 3b, the rst wing fragment .at 91 in Fig. 3c, and .theliirst ,.tailfragment at 92 in Fig. 3c. These pulse fragments'91 and 92 rare thensubjected to a second differentiation in a conventionalinductance-resistance fdifferentiator` circuit, asgindicated at 63 inFig. 1, to produce the second, or con-P plementaryY wing Afragment` 91band tail fragment 92b, as shown in Fig. 3d. It will be observed uponreference to Fig. 3b that the pulse squaring is accomplished in a mannerto produce a sharper slope on the leading edge of the pulse 4than on thetrailing edge; hence time interval t4-t3 is greater than tZ-tl andtherefore E, El t-. t1 Accordingly, the iirst'stage .of differentiationwill produce pulse vfragments .(91 and 92, Fig. 3c) which will differ inamplitude to a degree conforming Vto the ratio:

which difference will carry through the second differentiation stage,lasfillustrat'ed'rin Fig.: 3d, to cause tail pulsefra'gments`92a, 92bAto be shorter than wing pulse'fragments*'91a,91b. The 'complementaryhalves of the wing fragment, on the other hand, will equal each other inlength because the leading and trailing slopes of pulse fragment 9'1'are equal; and for a corresponding reason the complementary halves oftail fragments 92a, 92b are equal.

The pulse fragments 91a, 91h, 92a, and 92b (andtheir successivecounter-parts produced at the -cycle repetition rate) are introducedinto the azimuth synchro resolver 36 where `they are vectorially dividedfor rdistribution (as vector voltages) to the respective azimuth andelevation amplifiers '70 and 71; the magnitude of the voltage vectorcomponent entering each amplifier being vproportional to the azimuthdeviationrangle, as above explained. The vector voltage componententeringthe eleva-tion amplitiercombines with the sine wave amplitudevoltage entering the elevation amplifier from the elevation synchroresolver 37 and which sine wave amplitude voltage is established by theinter-'action of the sine wave input into the elevationsynchro 37 (fromthe oscillator "61 by way of supply line 65) with the magnetic`tieldsproduced in said synchro 37 by its angular deviation from vzerosetting in obedienceto the rotational e'ffort applied thereto insynchronism with the antenna elevating lmotion as heretofore described;the degree of suchv rotation being reiiected in the magnitude of theamplitude yof the sine wave, with'fthe sine wave amplitude shrinking toVzero when'thetracking antenna is `in the zero elevation or dead ahead'attitude and the amplitude rising to maximum when the tracking antennais in maximum elevation attitude. The sine wave amplitude is 'reected inthe signal supplied to the elevation amplifier 71 whereit combines withthe wing and tail signals supplied to said amplifier 71 from theresolver 36. Accordingly, as these combinedsignals are delivered by wayof the cathode follower circuits 78 and 79 leading from amplifiers 70and 71 to the four conventional horizontal and vertical deliectionplates of the cathode ray tube, they will coact (in a manner graphicallysuggested in Fig. 6) to produce upon the screen of the tube the completeimage representing both the Aattitude and the direction of flight of theaircraft in relation .to thecentral position constituting the planesobjective. Simultaneously, the range attenuation action of thecomponents indicated at 73 and 74 willl introduce into the image'formingsignals an attenuation factor which will control the overall dimensions,or contour, of the image as actually displayed upon the radarscope, sothat the shifting size of the image will indicate the degree of `changein distance intervening between the interceptor craft andits target.

The, position ofthe. image,V as distinguished from its `attitude andcontour,.is controlled primarily by the interaction of the positioningvoltages supplied to the deflection .plates.bylinesittandQ84.connectingsaid plates to the potentiometers 81 and 82 whose resistance valuesshift in synchronism with resolvers 36 and 37, respec-V Vclaims be givena broad interpretation commensurate with the scope of the inventionwithin the art.

What is claimed is:

1. A target display system comprising an antenna mounted for movement inazimuthV andV elevation with respect to that on which itis mounted, acathode ray tube having beam deflection apparatus, means connectedbetween said antenna and said beam deflection apparatus for providingbeam positioning signals representing the azimuthal and elevationalpositions of said antenna, means connected to said deflection apparatusfor causing the beam of said tube to describe a first line, meansconnected to said deflection apparatus for causing the beam of said tubeto 'describe a line intersecting said first line, said last named meansincluding a resolver for controlling the angle of intersection betweensaid first and second lines, and means connected between said antennaand said resolver for causing the output of said resolver to be secondline intersecting said first line, said third meansV controlled by theposition of said antenna with respect to i that on which it is mounted.

2. A target display system comprising an antenna mounted for movement inazimuth and elevation, a cathode ray tube having beam deflectionapparatus, first means connected between said antenna vand said beamdeflection apparatus for providing beam positioning 'ilection apparatusfor causing the beam of said tube to describe a pair of parallel linesintersecting said first line, said third'means including a resolver forcontrolling the angle of intersection between said first line and eachof said parallel lines, means connected between said antenna and saidresolver yfor causing the" output of said resolver to 'be controlled bythe position of said antenna, and signal attenuation devices included insaid second means and said third means, the attenuation of said devicesbeing controllable by an impressed range signal representing thedistance rfrom said antenna to a target.

3. A target `display system comprising an antenna mounted for movementin azimuth and elevation with respect to that on which it is mounted, afirst resolver, means connected 'between said antenna and said firstresolver for causing the output of said resolver to be indicative of theazimuthal position of said antenna with respect to that on which it ismounted, a second resolver,"

means connected between said antenna and saidsecond resolver to causethe output of said second resolver to be indicative of the elevationalposition of said antenna with respect to that on which it is mounted, acathode ray tube having beam deflection apparatus, means connected tosaid beam deflection apparatus for providing beam positioning signals tocause the beam of said tube to be positioned at a location correspondingto the position of said antenna, pulse shaping means coupled to'saidrstresolver, said pulse shaping means including an oscillator coupled tosaid second resolver and causing said beam to describe a first line anda pair of parallel linesY intersecting said first line, and meanscoupling the outputs of said first and second resolvers to saidV beamdeflection means.

4. A target display system comprising a directional antenna mounted formovement in azimuth and elevation,

-a receiver coupled to said antenna, means connected tol said antennaand responsive to the output of said receiver for causing said antennato track a target, a cathode ray tenna, second means connected to saiddeflection ap-Y paratus for causing the beam of said tube to describe afirst line, third means connected to said deflection kapparatus forcausing the 'beam of said tube to describe va signal representingthe'distancefrom said antenna to said target. Y

5. A target displayrsystem comprising an antenna mounted for movement inazimuth and elevation with respect to that on which it is mounted,acathode ray tube having beam deflection apparatus, means connectedbetween said antenna and said beam deflection apparatus for providingbeam Ypositioning signals representing the azimuthal and elevationalpositionns of said antenna, means connected to said deflection apparatusfor causing the beam of said tube to describe a first line, meansconnected to said deflection apparatus for causing the beam of said tubeto describe a line intersecting said first line, said last named meansincluding a resolver for controlling the angle of intersection betweensaid first and second lines, means connected between said antenna andsaid resolver for causing the output of said resolver to be controlledby the position of said antenna t with respect to that on which it ismounted, and signal attenuation apparatus included in said meansconnected to said beam deilection apparatus, said signal attenuationapparatus being responsive to a range signal representing the distancefrom said antenna to said target.

V6. A target display system comprising an antenna mounted for movementin azimuth and elevation with respect `to that on which it is mounted, afirst resolver, means connected between said antenna `and said firstresolver for causing the output of saidresolver to be indicative of theazimuthal position of` said antenna with respect to that on which it ismounted, a second resolver, means connected between said antenna andsaid second resolver to cause the output of said second resolver tennawith respect to that on which it is mounted, a cathode ray tube havingbeam deflection apparatus, means connected to said beam deflectionapparatus for providing beam positioning signals to cause the beam ofsaid tube to be positioned' at a location corresponding to thepositionof said antenna, pulse shaping means coupled to said firstresolver, said pulse shaping means including an oscillator coupled tosaid second resolver and causing said beam to describe a first line anda pairof parallel lines intersecting said first line, means couplingthe. outputs of said first and second resolvers to said beam deflectionmeans, and signal attenuation apparatus included in said means connectedto said beam deflection apparatus, said signal attenuation apparatusbeing responsive to a range signal representing the distance from saidantenna to said target.

References Cited in the file of this patent UNITED STATES PATENTS2,226,930 Hefele Dec. 31, 1940 2,427,905 Fyler Sept. 23, 1947 2,467,319King Apr. 12, 1949 2,530,060 Holdam Nov. 14, 1950 2,571,165 Rines Oct.16. 1951

